3plan: SNLP, TOCL, and TOPI planners

This directory contains contains 3 comparable planners -- SNLP, TOCL,
and TOPI -- along with domain and testing information. SNLP is a
domain independent systematic conjunctive nonlinear (partial-order)
planner that is both complete and sound, TOCL is a total ordered
version of SNLP, and TOPI is a backward chaining planner.
The planners were created for comparing linear and nonlinear
planning in the Barrett and Weld paper.